Parsing of parenthesis with sed using regex

Question

I am looking for a command in sed which transforms this input stream:

dummy
(key1)
(key2)dummy(key3)
dummy(key4)dummy
dummy(key5)dummy))))dummy
         


        

Answer 1

In Perl, you can use Marpa, a general BNF parser — the parser code is in this gist.

BNF parser is arguably more maintainable than a regex. Parens around grammar symbols hide their values from the parse tree thus simplifying the post-processing.

Hope this helps.